electronics, engineering, physics, science

Guide to Battery Sizes

D battery: 33.2 mm. in diameter x 61.5 mm. long. Minimum capacity (alkaline): 12,000 mAh

Was once commonly used in large flashlights, lanterns, and children’s toys.

C battery: 26.2 mm. in diameter x 50 mm. long. Minimum capacity (alkaline): 10,000 mAh

Was once commonly used in large and small flashlights and children’s toys.

B battery: 21.5 mm. in diameter x 60 mm. long. Minimum capacity (alkaline): 8,000 mAh

Used in the UK and the Russian Federation as the internal cells of 4.5-volt lantern batteries.

A battery: 17 mm. in diameter x 50 mm. long. Minimum capacity (alkaline): 4,900 mAh

Not commonly available as a primary (non-rechargeable) battery. Sometimes encountered as a rechargeable battery in battery packs.

AA battery: 14.5 mm. in diameter x 50.5 mm. long. Minimum capacity (alkaline): 1,800 mAh

Still in widespread use. Commonly available in alkaline, carbon-zinc, nickel-metal-hydride, and nickel-cadmium varieties. Used for small portable devices like flashlights and portable electronics.

AAA battery: 10.5 mm. in diameter x 44.5 mm. long. Minimum capacity (alkaline): 860 mAh

Still in widespread use. Commonly available in alkaline, zinc-carbon, nickel-metal-hydride, and nickel-cadmium varieties. Used for small portable devices like small flashlights, small portable electronics, and electronics with a low current draw.

AAAA battery: 8.3 mm. in diameter x 42.5 mm. long. Minimum capacity (alkaline): 500 mAh

Available, but not in common use. Used for slim-profile electronics such as laser pointers and penlights.

AAAAA battery: 7 mm. in diameter x 39.9 mm. long. Minimum capacity (alkaline): 330 mAh

Briefly considered for use in endoscopic surgical equipment in the early 1980s, because of its narrow profile, but rejected due to the risk of electrolyte leakage within patients.

AAAAAA battery: 5.6 mm. in diameter x 37.6 mm. long. Minimum capacity (alkaline): 190 mAh

Developed in the USSR in the mid-1970s, to be used as both the projectile and the power source for the guidance system in AK-48 cartridges. Saw limited mass-production, and continued to be used following the collapse of the USSR. Was rendered entirely obsolete by the development of the Zorg ZF-1 in 1997.

AAAAAAAAAA: 2.3 mm. in diameter x 29.5 mm. long. Minimum capacity (alkaline): 19 mAh

Showed promise powering ultra-portable and ingestible electronic devices. However, manufacturer Varta produced a battery in this size with the name shortened to A10, which resulted in a trademark dispute with Fairchild, manufacture of the A-10 “Warthog” attack aircraft, and caused Varta and other manufacturers to cease production out of fear of litigation.

AAAAAAAAAAAAAAA: 0.8 mm. in diameter x 21.8 mm. long. Minimum capacity (alkaline): 1 mAh

Not in common use, but favored by some for electric mechanical pencils, being about the same size as a pencil lead.

AAAAAAAAAAAAAAAAAAA: 0.31 mm. in diameter x 17.1 mm. long. Minimum capacity (alkaline): 0.11 mAh

Fell out of favor in the 1980s because it was frequently mistaken for a 30-gauge hypodermic needle. Was banned in the early 1990s after it was discovered teenagers were using them to inject themselves with intravenous POWER.

AAAAAAAAAAAAAAAAAAAAAAAAA: 0.085 mm. in diameter x 11.88 mm. long. Minimum capacity (alkaline): 0.00038 mAh

Were briefly considered for portable power applications in the 1980s, since they could easily be disguised as strands of hair, but were never mass-produced due to their low capacity.

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA: 0.0093 mm. in diameter x 6.48 mm. long. Minimum capacity (alkaline): 0.000013 mAh

Were briefly believed to be the power source for human cells, until the discovery of the mitochondrion in 1898.

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA: 0.001 mm. in diameter x 3.7 mm. long. Minimum capacity (alkaline): 0.00000000015 mAh

Were most likely first observed in 1943 in a bacterial mat from the northern part of the Dead Sea. Were misidentified as “funny-looking bacteria” until 2003.

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA: 0.000010 mm. diameter x 0.65 mm. long. Minimum capacity (alkaline): 0.00000000000049 mAh

Showed promise as a power source for ultraminiature cassette players in the 1980s, but fell out of favor due to its physical resemblance to particles of Ebola virus.


An alkaline AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA battery manufactured by Panasonic held the world record for smallest alkaline battery from its introduction in 1990 until 2004. In 2004, it was discovered that the battery’s nominal diameter was smaller than that of a hydrogen atom, and its capacity was fifty times smaller than the fundamental charge of an electron. The battery was stricken from the record books for being “physically impossible”. Panasonic retired this battery size the following year.

This entire post is a work of fiction. Any resemblance to real persons or entities is coincidental.

astronomy, image, pixel art, science, short, Space, Uncategorized

Pixel Solar System


(Click for full view.)

(Don’t worry. I’ve got one more bit of pixel art on the back burner, and after that, I’ll give it a break for a while.)

This is our solar system. Each pixel represents one astronomical unit, which is the average distance between Earth and Sun: 1 AU, 150 million kilometers, 93.0 million miles, 8 light-minutes and 19 light-seconds, 35,661 United States diameters, 389 times the Earth-Moon distance, or a 326-year road trip, if you drive 12 hours a day every day at roughly highway speed. Each row is 1000 pixels (1000 AU) across, and the slices are stacked so they fit in a reasonably-shaped image.

At the top-left of the image is a yellow dot representing the Sun. Mercury and Venus aren’t visible in this image. The next major body is the blue dot representing the Earth. Next comes a red dot representing Mars. Then Jupiter (peachy orange), Saturn (a salmon-pink color, which is two pixels wide because the difference between Saturn’s closest and furthest distance from the Sun is just about 1 AU), Uranus (cyan, elongated for the same reason), Neptune (deep-blue), Pluto (brick-red, extending slightly within the orbit of Neptune and extending significantly farther out), Sedna (a slightly unpleasant brownish), the Voyager 2 probe (yellow, inside the stripe for Sedna), Planet Nine (purple, if it exists; the orbits are quite approximate and overlap a fair bit with Sedna’s orbit). Then comes the Oort Cloud (light-blue), which extends ridiculously far and may be where some of our comets come from. After a large gap comes Proxima Centauri, the nearest (known) star, in orange. Alpha Centauri (the nearest star system known to host a planet) comes surprisingly far down, in yellow. All told, the image covers just over 5 light-years.

geology, image, physics, science, short

Pixel Earth 1

I present you: a scale model of the Earth’s surface, from an altitude of 400 kilometers down to a depth of 300 kilometers. At this scale, every pixel is 1 km by 1 km.crust-1-px-eq-1-km-numbered-large


  1. The International Space Station at perigee.
  2. The aurora borealis.
  3. The greatest altitude at which human beings have died: cosmonoauts Georgy Dobrovolsky, Vladislav Volkov, and Viktor Patsayev died just before the reentry of Soyuz 11, when the explosive decoupling of the descent module opened an oxygen seal in the cockpit.
  4. The highest altitude reached by the Air Force’s X-15, which still holds the speed record for a crewed aircraft, and which was among the first crewed vehicles to cross into space.
  5. The official edge of space: the Kármán line, at around 100 kilometers altitude. Above this line, you have to move faster than orbital velocity for wings to provide usable lift, so you might as well just orbit.
  6. The streak denotes the range of altitudes at which meteors glow.
  7. The streak denotes the altitudes at which the 2013 Chelyabinsk meteorite glowed. The starburst denotes the approximate altitude at which it exploded.
  8. The altitude at which the Space Shuttle Columbia stopped sending telemetry and began its final breakup.
  9. On a less sad note: the altitude from which Felix Baumgartner began his famous skydive.
  10. The top of the troposphere (where weather happens); the beginning of the stratosphere; the top of thunderstorms in middle and tropical latitudes.
  11. 10,000 meters: the altitude at which passenger airplanes cruise.
  12. The summit of Mt. Everest.
  13. The Challenger Deep (over 10,000 meters deep).
  14. The deepest active mining operation: 4,000 meters, at the Mpomeng gold mine in South Africa.
  15. The deepest human beings have ever drilled: 12 kilometers at the Kola Superdeep Borehole, in Russia.
  16. The deepest confirmed location in a natural cave: 2 km, in Krubera Cave, in Abkhazia, Georgia (the Eastern European Georgia, not the American one.) The cave very likely goes deeper.
  17. Volcanic magma chambers. Contrary to popular belief, most of the mantle is a plastic solid (like very, very stiff Silly Putty), rather than molten. Magma is the exception. The magma chamber that feeds Hawai’i’s volcanoes is on the shallow end of the spectrum. The magma chamber underneath the Yellowstone Caldera (which provides heat for Yellowstone’s famous geysers) sits at around 25 to 35 kilometers deep. We have actual rough maps of it. It’s awesome.
  18. The Mohorovičić discontinuity (or Moho; no, not the KSP one): the official boundary between crust and mantle. It can be as shallow as 5 kilometers deep (beneath the seafloor) and 90 kilometers deep (under mountains); it averages 35 kilometers deep.
  19. Very deep magma chambers.
  20. The end of the asthenosphere, a region of rock made weak and squishy (relatively speaking) by the enormous temperature and pressure. This starts beneath the solid crust (the lithosphere). Its boundary isn’t well-defined.
  21. A hot plume in the upper mantle. Droplets (well, droplet-sized compared to the whole Earth) of lower-melting-point material rise through the mantle to fill magma chambers.

(I should point out that I’m not a geologist. If I’ve made a mistake, please let me know. You won’t hurt my feelings. I’d rather admit I’m wrong than put out a misleading graphic.)

image, short, Space

Earth versus Sun

Earth vs Sun at 1 AU.png

Nothing too special here: just a size comparison between the Earth and the Sun. The only difference from the usual ones, is that I’ve based their relative sizes on their angular diameters. For the Sun, I computed the angular diameter at a distance of 1 AU (which is how we see it here on Earth). For the Earth, I computed the angular diameter at a distance of 1 AU minus the diameter of the Sun. In other words, the Earth appears as large as it would if it were sitting at the point on the Solar surface nearest us. This is how the Earth would look as a very unfortunate close-transiting planet.

To paraphrase Carl Sagan: that little blue blob is home. That’s us. Everything that’s ever happened to you happened there.

Now consider that compared to the Sun…

Earth vs Sun Closeup.png

Here’s a closeup of the same image, showing the Earth compared to the weird convection granules on the Sun’s surface.

Both images are from NASA. The Solar image is from the Solar Dynamics Observatory (HMI intensitygram, February 7th, 2016), and the Earth-disk image is from the GOES earth-observing satellite.


Charlotte vs. The Comet 2: This Time, I Got It Right

A few weeks ago, I posted a scale comparison between comet 67P/Churyumov-Gerasimenko and the city of Charlotte, North Carolina, the city I live in. It was wildly, offensively inaccurate: somehow, I shrank the comet by a factor of five. Well, now that the ESA has finally released their shape model for the comet, I can just import the model into Blender, convert it into a .dae file, scale it until it’s (approximately) the right size, and stick it in Google Earth to get an idea of the comet’s scale.

67 P vs. Charlotte NC

The larger lobe is 4,100 meters long, and the whole comet dwarfs Charlotte. In fact, it looks like Charlotte is being menaced by a legless puppy. There’s an image for you…